CT IN STROKE - INTERRATER VARIABILITY AND VALIDITY OF A SIMPLE DOCUMENTATION SYSTEM

A simple CT documentation system for frequently encountered stroke lesions was developed for use in a stroke data bank. Each lesion is documented by means of a three-digit code that corresponds either to a specific type of local infarction, an arterial territory, or several generalized changes of the brain. In addition, the density without contrast, enhancement status, oedema, size of the lesion, and clinical relevance of the lesion are documented. 13 CT scans regarded as representative and characteristic for stroke patients were independently evaluated by ten neuroradiologists from seven institutions. The interrater agreement was very good for haemorrhages, lacunae as well as for territorial and border zone infarctions. The variability between the raters was most marked for generalized alterations, especially for multiple infarctions, Binswanger's disease, lacunar state, and leucoaraiosis. This variation is most likely due to the aetiological heterogeneity and varying appearances of such changes on CT scans. Thus, the validity of this documentation of stroke lesions, as seen on routine CT scans, appears to be acceptable.